I keep seeing this brought up as proof we go straight to heaven but if you look the word " today" in that scripture in the concordance you won't find it. King James Version says " to Day" its two words and it changes the meaning. In my study what I found Jesus to be saying is: " Forever, shalt thou be with me in paradise" it upsets me that everyone says today, when the word today is not there. Has anyone else realized this?
Strong's Concordance identifies the word as an adverb that means "today" or "now."
Your question appears to rest on the idea that "to day" and "today" have substantially different meanings. To this I must add "this day," as the original Greek is also translated that way. Therefore, are they, indeed, different?
Frankly, they are not. The definition of the function word "to,"1 while quite lengthy and involved, boils down to indicating movement toward or identifying a relation. In other words, "to day" means "toward the day" or "in relation to the day," which is not dissimilar to the definition of "today."
This is substantially supported by the translation from the Greek to "this day."
A cursory search of the Internet reveals that "today" began as Old English "tó dæg" meaning "on (this) day." During the 14th century (the period of Geoffrey Chaucer) it became "to-day" (with an hyphen). It was written that way until the beginning of the 20th century, afterwhich it was written "today." During all that time, the meaning did not change.
Finally, I do not understand how you converted "to day" into "forever." My answer may change if you provide a detailed explanation of how you came to that conclusion.
1 The etymology of the preposition "to" relates to the words "tó" (old English), "toe" (Dutch), and "zu" (German). While the modern meaning has become refined due to continued use over the centuries, the basic meaning has not changed.
First, "to day" is older English for the one linguistic unit (what has been joined over the centuries into) "today". Meaning 'this day'.
It doesn't convey two different ideasfor each word, especially since separately they mean nothing.
Besides, you are working with a faulty assumption "King James Version says " to Day" its two words and it changes the meaning". Because of the above, but also, if it were two words ("to day" is actually one word or at least one linguistic unit) because one Greek word may not always have a one word equivalent. For example, the honorific given to Mary in Luke 1:28 (κεχαριτωμένη—"that has been graced [by God]"). Or Exodus 20:14: ου μοιχευσεις ("Thou shalt not commit adultery").
And Jesus said to him: Amen I say to thee, this day [σήμερον] thou shalt be with me in paradise [Παραδείσῳ].
The Greek word σήμερον (sēmeron) means 'today' or 'this day.' With the nuance of 'even now, soon, or just past.'
This same God hath fulfilled to our children, raising up Jesus, as in the second psalm also is written: Thou art my Son, this day [σήμερον] have I begotten thee.
We know this means today for sure, because it's quoting Psalm 2:7 (where the word translates הַיּ֥וֹם haYowm—"this day; today." (LXX, or Greek Old Testament: σήμερον).
Besides, Jesus was not "in the heart of the earth" (Matthew 12:40) or "preaching to the spirits in prison"—Abraham's Bosom (1 Peter 3:19) or "descended into the lower parts of the earth" (Ephesians 4:9), "forever" (NOT a translation of the Greek word σήμερον). But "for three days" (Matthew 12:40). The day Jesus died, He didn't go immediately to heaven with the good thief, they went to παράδεισος (paradeisos) or Abraham's Bosom (Luke 16:21-23). Since His Ascension (and opening of heaven) and glorification of the saints who were "in prison" until heaven was opened, no one goes to that abode any longer, but to Heaven or Hell (or Purgatory) (the latter two of which come under ᾍδης Hades, or the realm of the dead).